Record-replay in Fission

October 16, 2018

Fission Functions are triggered by events. We’ve recently added a new
feature that allows you to record these events into a database,
examine these recordings, and replay them for testing and
troubleshooting.

Functions are often part of a larger, more complex system, that can
take a while to test. Sometimes, tests might not be fully automated
and require some human interaction. In both cases, you can record the
events that trigger the function and simply use the same events to
re-test the function. The recorded events can be replayed on
different versions of a function, essentially functioning as an
automated test.

Recording can also useful in production – for example, you can enable
recording for a subset of function invocations that error out, and use
those recorded events later to test bugfixes.

Fission is the first serverless function framework to offer out-of-the
box record-replay.

Using record-replay in Fission

Record replay is available from Fission 0.11 onwards. You can enable
recording for a function or a trigger. This section will guide you
through using record replay on a simple function in Python.